Method of making a pilot operated valve positioner

ABSTRACT

A pilot operated valve positioner having a pilot valve unit operated by a pneumatic signal to pneumatically operate an actuator unit carrying a main valve member to position the same relative to its main valve seat in a valve unit in relation to the magnitude of the pneumatic signal, the actuator unit having a range spring and a feedback spring for the pilot valve unit. The springs are coiled compression springs and are substantially concentrically mounted. The pilot valve unit has a feedback positioning diaphragm and part of its housing concentrically disposed in one end of the range spring to render the valve positioner relatively small and compact.

This application is a divisional patent application of its copendingparent application, Ser. No. 800,299, filed May 25, 1977, now U.S. Pat.No. 4,143,850 issued Mar. 13, 1979.

This invention relates to a pilot operated valve positioner and to amethod of making the same.

It is well known to provide a pilot operated valve positioner havingpilot valve means operated by a pneumatic signal to pneumaticallyoperate an actuator means carrying a main valve member to position thesame relative to its main valve seat in a valve unit in relation to themagnitude of the pneumatic signal.

However, it has been found, according to the teachings of thisinvention, that such a pilot operated valve positioner can be uniquelyarranged in a manner hereinafter set forth to render the valvepositioner relatively small and compact.

Such pilot operated valve positioner of this invention readily lendsitself to be an exhaust gas recirculation valve unit for an internalcombustion engine to be operated by the signal conditioner system ofapplicant's copending patent application, Ser. No. 800,211, filed May25, 1977, now U.S. Pat. No. 4,099,539, or other signal producing meansas desired.

In particular, the pilot operated valve positioner of this invention hasthe range spring and the pilot valve means feedback spring formed ascoiled compression springs that are disposed substantiallyconcentrically in an atmospheric chamber of the actuator unit. The pilotvalve means has a feedback positioning diaphragm means and part of itshousing means concentrically disposed in one end of the range spring torender the valve positioner relatively small and compact as well assubstantially leak proof.

Accordingly, it is an object of this invention to provide an improvedpilot operated valve positioner having one or more of the novel featuresof this invention as set forth above or hereinafter shown or described.

Another object of this invention is to provide a method of making such apilot operated valve positioner, the method of this invention having oneor more of the novel features of this invention as set forth above orhereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from areading of the description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

The single FIGURE of the drawings is an enlarged, fragmentary,cross-sectional view illustrating the improved pilot operated valvepositioner of this invention.

While the various features of this invention are hereinafter describedand illustrated as being particularly adapted to provide a pilotoperated valve positioner to operate as an exhaust gas recirculationvalve for an internal combustion engine, it is to be understood that thevarious features of this invention can be utilized singly or in anycombination thereof to provide a pilot operated valve positioner forother uses as desired.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to the drawings, the improved pilot operated valvepositioner of this invention is generally indicated by the referencenumeral 11 and includes three units 12, 13, and 14 disposed in stackedaligned relation to provide a self-contained pilot operated valvepositioner 11, the unit 12 comprising a pilot valve means, the unit 13comprising an actuator means, and the unit 14 comprising a main valvemeans.

The main valve means or unit 14 includes a housing means 15 having aninlet 16 and an outlet 17 with substantially a frusto-conical valve seat18 therebetween adapted to be controlled by a movable valve member 19having its stem 20 interconnected to a movable diaphragm means 21 of theactuator unit 13 to be controlled thereby in a manner hereinafterdescribed.

The actuator unit 13 and pilot valve unit 12 cooperate in a mannerhereinafter described to position the valve member 19 of the valve unit14 in various open positions thereof relative to the valve seat 18 inaccordance with the magnitude of a changeable pneumatic signal beingdirected to a nipple means 22 of the pilot valve unit 12 from a signalproducing source 23, such as the signal producing source of theaforementioned co-pending patent application.

Also, it may be found that an electronic system can be utilized todirect a changing pneumatic signal to the pilot valve means 12 eventhough the pilot operated valve positioner 11 of this invention is to beutilized as an exhaust gas recirculation valve for an internalcombustion engine or the like and be operated by vacuum rather than bypressure.

In any event, the details and the operation of the pilot operated valvepositioner 11 of this invention will now be described.

As illustrated, the actuator unit 13 includes two substantiallycup-shaped housing parts 33 and 34 having their open ends 35 and 36crimped together to hold the outer peripheral means 37 of a flexiblediaphragm 38 therebetween, the flexible diaphragm 38 forming part of thediaphragm means 21 of the actuator means 13 and dividing the housingmeans 33, 34 thereof into two chambers 39 and 40 on opposite sidesthereof.

The chamber 39 of the actuator unit 13 is adapted to be interconnectedto the atmosphere through suitable vent openings 41 formed in thehousing means 33.

The chamber 40 of the actuator unit 13 is sealed from the atmosphere andis adapted to be interconnected by a nipple means 42 to a conduit means43 that is interconnected to an outlet nipple 44 of the pilot unit 12for a purpose hereinafter described.

The valve stem 20 of the valve unit 14 has its upper end 45 projectingthrough suitable seal means 46 in the housing means 34 of the actuatorunit 13 to be fastened to the diaphragm means 21 in any suitable mannerso that the valve stem 20 will be moved upwardly and downwardly uponupward and downward movement of the diaphragm means 21 of the actuatorunit 13 whereby the valve member 19 will be positioned relative to thevalve seat 18 depending upon the position of the diaphragm means 21 inthe actuator unit 13.

The pilot valve means or unit 12 includes a housing means 47 thatprojects partially into an opening 48 formed in the closed end 49 of thehousing part 33 of the actuator unit 13 and is secured thereto in anysuitable manner.

The housing means 47 of the pilot valve unit 12 includes a valve seat 50separating an inlet nipple 51 from the outlet nipple 44, the valve seat50 being adapted to be opened and closed by a movable disc valve member52 normally urged to its closed position by a compression spring 53. Thevalve member 52 of the pilot valve unit 12 is controlled by a hollowvalve member 54 having one end 55 projecting through the valve seat 50and engaging the valve member 52 while the other end 56 thereof isenlarged and engages a flexible diaphragm 57 of a diaphragm stack 58that comprises another diaphragm 59 separated from the first diaphragm57 by a spacer means 60. The spacer means 60 has a passage 61 thereinthat leads to a central opening 62 in the diaphragm 57 and to a ventopening 63 in the housing means 47 for a prupose hereinafter described,the enlarged end 56 of the hollow valve member 54 being large enough toclose off the opening 62 in the diaphragm 57 when seated thereagainst inthe manner illustrated for a purpose hereinafter described.

The diaphragm stack 58 of the pilot valve unit 12 is interconnected bypost means 64 to a feedback diaphragm 65 carried by the housing means 47at the lower end thereof for a purpose hereinafter described.

A relatively large coiled compression range spring 66 is disposed in theatmospheric chamber 39 of the actuator unit 13 and has one end 67bearing against the movable diaphragm means 21 thereof and the other endthereof bearing against the closed end 49 of the housing part 33 wherebythe force of the range spring 66 tends to urge the diaphragm means 21downwardly and thereby maintain the valve member 19 in its closedposition against the valve seat 18 as illustrated.

A coiled compression feedback spring 69 is also disposed in theatmospheric chamber 39 of the actuator unit 13 and is concentricallymounted within the larger coiled range spring 66, the coiled compressionfeedback spring 69 having one end 70 thereof bearing against thediaphragm means 21 of the actuator unit 13 and the other end 71 thereofbearing against the feedback diaphragm 65 of the pilot valve unit 12 fora purpose hereinafter described.

It is believed that by concentrically mounting the feedback and rangesprings 69 and 66 as well as projecting part of the housing 47 of thepilot unit 12 concentrically within the coiled range spring 66 in themanner illustrated, the pilot operated valve positioner 11 is renderedsubstantially small and compact to operate in a manner now to bedescribed.

Assume that a pressure supply 73 is interconnected to the inlet nipple51 of the pilot valve unit 12 of the pilot operated valve positioner 11of this invention. Also, assume that a changeable pressure signal source23 is interconnected to the nipple 22 of the pilot valve unit 12.

For example, the pressure supply 73 can comprise the air pump of theinternal combustion engine control system of the aforementionedco-pending patent application while the source 23 can comprise thesignal source produced by its engine control system of theaforementioned co-pending patent application.

In any event, an increasing pressure signal into a signal chamber 72 ofthe pilot valve unit 12 defined between the housing means 47 thereof andthe upper diaphragm 59 of the diaphragm stack 58 will tend to urge thediaphragm stack 58 downwardly in opposition to the force of thecompression spring 53 tending to maintain the valve member 52 in itsclosed position against the valve seat 50 as well as in opposition tothe force of the feedback spring 69 tending to maintain the diaphragmfeedback 65 in an up position thereof. As long as the valve member 52remains in the closed condition against the valve seat 50, the force ofthe pneumatic signal in the chamber 72 is insufficient to cause arepositioning of the valve positioner 11 of this invention.

However, when the force of the pneumatic signal in the chamber 72 issufficient to open the valve member 52 away from the valve seat 50 ofthe pilot unit 12, the pressure source at the inlet nipple 51 is adaptedto be interconnected to the outlet nipple 44 whereby the conduit means43 directs the fluid pressure into the chamber 40 of the actuator unit13 to act against the diaphragm means 21 and tend to move the sameupwardly in opposition to the force of the compression spring 66 as wellas in opposition to the smaller force of the feedback compression spring69.

When the pressure in the chamber 40 is sufficient to move the diaphragmmeans 21 upwardly in opposition to the spring forces, the diaphragmmeans 21 moves upwardly and pulls the valve stem 20 and valve member 19therewith to open the valve seat 18 a certain amount. The upwardmovement of the diaphragm means 21 continues until the force of thefeedback compression spring 69 being compressed between the feedbackdiaphragm 65 and the upwardly moving diaphragm means 21 is sufficient tomove the feedback diaphragm 65 upwardly to permit the valve member 52 toagain close against the valve seat 50 as illustrated whereby the supplyof air pressure to the chamber 40 of the actuator 13 is now terminatedand the diaphragm means 21 remains in its new position to hold the valvemember 19 in a certain open position relative to the valve seat 18.Thus, the open valve seat 18 is now adapted to supply fluid, such as theinternal combustion engine exhaust gas, at the inlet 16 to the outlet 17thereof at a certain rate in accordance with the force of the pneumaticsignal in the signal chamber 72 of the pilot valve unit 12 as previouslydescribed, the outlet 17 being adapted to direct the fluid flowtherefrom back to the intake manifold of the internal combustion engine.

A subsequent change in the magnitude of the pneumatic signal beingdirected to the chamber 72 of the pilot valve unit 12 cause a furtherrepositioning of the valve member 19 relative to the valve seat 18. Forexample, a further increase in the magnitude of the signal to thechamber 72 again causes further opening of the valve member 19 relativeto the valve seat 18 in the manner previously described by causing areopening of the valve member 52 to permit an additional amount of fluidpressure to be directed to the chamber 40 until the feedback spring 69again recloses the valve member 52 as previously described. Conversely,a decrease in the magnitude of the pneumatic signal in the signalchamber 72 of the pilot valve unit 12 causes the feedback compressionspring 69 to move the feedback diaphragm 65 upwardly and through thepost means 64 move the upper diaphragm stack 58 upwardly so that thetubular valve member 54 removes away from the closed valve member 52 andpermits the outlet nipple 44 to be interconnected through the opening 62in the diaphragm stack 58 to the vent opening 63 whereby some of thepressure in the actuator chamber 40 is now vented into the atmosphere toreduce the pressure in the chamber 40 so that the force of thecompression spring 66 can move the diaphragm means 21 downwardly and,thus, close the valve member 19 toward the valve seat 18 a certainamount. The downward movement of the diaphragm means 21 and, thus, theclosing movement of the valve member 19 relative to the valve seat 18terminates when the reducing force of the compression spring 69 is suchthat the force of the signal in the signal chamber 72 of the pilot valvemeans 12 is sufficient to move the diaphragm stack 58 thereof downwardlyto close the opening 60 of the diaphragm stack 58 by compressing thetubular valve member 54 between the lower diaphragm 57 and the valvemember 52 as illustrated so that the venting of the pressure in theactuator chamber 40 of the actuator unit 13 now ceases and the diaphragmmeans 21 is held in its new position.

Therefore, it can be seen that the pilot operated valve positioner 11 ofthis invention is adapted to position the valve member 19 relative tothe valve seat 18 in relation to the value of the pneumatic signal beingfed to the signal chamber 72 of the pilot unit 12 as previouslydescribed.

It is believed that by concentrically mounting the feedback spring 69 inthe range spring 66 as well as concentrically disposing part of thehousing means 47 of the pilot unit 12 in the range spring 66, arelatively small and compact pilot operated valve positioner 11 isprovided that can accurately control the valve unit 14 in the mannerpreviously described without having adverse seal and leakage problemssince the valve stem 20 of the valve unit 14 is sealed at the upper endthereof by the diaphragm means 21 of the actuator unit 13 and does notform part of the feedback means for the pilot valve unit 12 as thefeedback spring 69 performs such function.

Thus, it can be seen that this invention not only provides an improvedpilot operated valve positioner, but also this invention provides animproved method of making the same.

While the form and method of this invention now preferred has beenillustrated and described as required by the Patent Statute, it is to beunderstood that other forms and method steps can be utilized and stillfall within the scope of the appended claims.

I claim:
 1. In a method of making a pilot operated valve positionerhaving pilot valve means operated by a pneumatic signal to pneumaticallyoperate an actuator means carrying a main valve member to position thesame relative to its main valve seat in a valve unit in relation to themagnitude of said pneumatic signal, said actuator means having a rangespring and a feedback spring for said pilot valve means, said springsbeing coiled compression springs and being substantially concentricallymounted, the improvement comprising the step of disposing part of thehousing means of the pilot valve means concentrically within one end ofsaid range spring of said actuator means so that a positioning diaphragmmeans of said pilot valve means is also concentrically disposed in saidone end of said range spring and engages one end of said feedback springto render said valve positioner relatively small and compact.
 2. Amethod as set forth in claim 1 and including the steps of forming saidactuator means with a positioning diaphragm means, and disposing saidfeedback spring between said positioning diaphragm means of saidactuator means and said positioning diaphragm means of said pilot valvemeans so as to be operatively associated therewith.
 3. A method as setforth in claim 2 and including the step of bearing the other opposed endof said feedback spring against said positioning diaphragm means of saidactuator means.
 4. A method as set forth in claim 2 and including thesteps of forming said actuator means with an atmospheric chamberdisposed on one side of said positioning diaphragm thereof, anddisposing said springs in said atmospheric chamber.
 5. The method as setforth in claim 1 wherein said step of disposing part of said housingmeans of the pilot valve means concentrically within one end of saidrange spring comprises the steps of telescoping part of said housingmeans of said pilot valve means within an open end of a housing part ofsaid valve positioner, and securing said telescoped parts together.